The hydroformylation reaction, also known as the oxo reaction, is used extensively in commercial processes for the preparation of aldehydes by the reaction of one mole of an olefin with one mole each of hydrogen and carbon monoxide. The most extensive use of the reaction is in the preparation of normal- and iso-butyraldehyde from propylene. The ratio of the amounts of the normal- to iso-aldehyde products typically is referred to as the normal- to iso-aldehyde (N:I) ratio or the normal- to branched-aldehyde (N:B) ratio. In the case of propylene, the normal- and iso-butyraldehydes obtained from propylene are in turn converted into many commercially valuable chemical products such as, for example, n-butanol, 2-ethyl-hexanol, n-butyric acid, iso-butanol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, the mono-isobutyrate and di-isobutyrate esters of 2,2,4-trimethyl-1,3-propanediol. The hydroformylation of higher α-olefins such as 1-octene, 1-hexene, and 1-decene yield aldehyde products which are useful feedstocks for the preparation of detergent alcohols and plasticizer alcohols. The hydroformylation of substituted olefins such as allyl alcohol is useful for the production of other commercially valuable products such as 1,4-butanediol. Because the demand for the downstream products made from normal- and iso-aldehydes varies as a result of periodic market needs, longer-term market trends, and shorter-term process dynamics such as inventory control, there is often a need to vary the normal- to iso-aldehyde ratio during normal process operations.
Although different hydroformylation catalyst systems produce different nominal normal- to iso-aldehyde ratios, it is advantageous to vary the normal- to iso-aldehyde ratios during normal process operation without changing the catalyst system and by employing only modest changes in process conditions that are readily varied during normal operations.